Twin Sense
by Midnight Lupus
Summary: When Dipper goes out looking for the Hide Behind, he encounters something a whole lot worse. Mabel is guided to her brother by that innate sixth sense possessed by twins, but finding him might just endanger him further.
1. Chapter 1

It was common knowledge to the residents of Gravity Falls, Oregon and indeed to most of the world that twins had a sixth sense; this sense was undefinable, undeniable, and could manifest in various forms. Dipper and Mabel Pines were no exception; each twin possessed, somewhere deep within their minds, a tiny instinct that alerted them to the condition of their other half. Their parents had at first exchanged bemused glances when one of their children had insisted that they knew what the other was doing; those glances had changed to amazement when one day Mabel had insisted that they rush home from dance practice because Dipper had an "ouch" only to discover their son icing a badly sprained ankle.

It was hard to tell when that tiny sense developed within the siblings; Dipper was convinced that they had been born with it already fully formed, but Mabel insisted that it had developed when they had first set eyes on one another as babies and had strengthened during their early years. Her memories of being a toddler were hazy, but one of the clearest recollections she possessed from those times was a feeling of emptiness that would only dissipate when she had climbed into her brother's crib—after a few nights of that her parents had taken the hint and had purchased a single, larger crib for them to share. She firmly believed that the knowledge she'd possessed, that her twin was somewhere nearby even though she couldn't necessarily see him, had been the start of her sixth sense.

Over time that knowledge had taken a firm root in the back of her mind, and she had but to close her eyes and concentrate to feel the state of her brother, no matter how far apart they were. Dipper had always been a sensitive child, and had honed his sixth sense to the degree that sometimes he would hand an item to his sister before she even asked for it. Occasionally at night when he couldn't sleep, he would pay attention to that small instinct and the information that his mind received-that Mabel was sleeping soundly- would catch on and lull him into peaceful slumber.

Stan Pines knew that his great niece and nephew had an uncanny connection; they were so in tune with one another that occasionally it was eerie. To be honest though it made him feel better that they were aware of one another's condition; he worried when one of them went off on their own, but if the other was home having a good time then he knew all was well. That twin sense was the only reason he wasn't out looking for his great-nephew right now.

Dipper had left earlier that afternoon, when the sun was just past its highest point, to go hunt for the Hide Behind. Stan had shaken his head in resignation, no matter what he told the kid, he wasn't going to drop whatever he'd read in that stupid journal. Mabel had elected to stay behind with Grunkle Stan, claiming that she'd already seen a maraca playing owl and wasn't going to hike all the way out into the woods to find another. With a glare and a firm "it's out there Mabel!" Dipper had shut the door and had bounded across the lawn into the shadows of the forest.

That had been several hours ago. Outside the shadows slanted drastically as the sun dipped low on the horizon; the woodpeckers were changing shifts with the bats, and the crickets were just tuning up for their nightly concert. Wendy and Soos had left the Mystery Shack a while ago at the end of their shift, leaving Stan, Mabel, and Waddles to themselves. Currently the television was blaring the most recent episode of "Baby Fights" and Stan had parked himself in his usual armchair. Unusually, however, he was still dressed and very awake, his fingers tapping on the armrest where Dipper liked to perch. It wasn't that he was worried for the kid… Dipper could take care of himself. It was just getting sort of late… there were bears and a lot of other stuff… he was worried.

He hadn't gotten up to go look yet, he'd give it another hour; besides, Mabel was happily playing a combination of hopscotch and go fish with Waddles. From her attitude she could sense nothing amiss with her twin, and that assuaged some of Stan's concerns. Taking a moment, Stan turned and watched his great-niece with an amused smile; he had no clue what the rules were for her game, but she seemed to be enjoying herself immensely. Grumbling to himself, the man settled down further into the armchair and tried to concentrate on the fight; behind him the regular scuffing of Mabel's shoes against the wooden floors was a subtle backbeat.

Mabel completed her turn and drew another card, grinning as Waddles ate two of his.

"You've gotta go hopscotch now!"

Obediently the pig shuffled around a few times before settling down and nosing a card.

Mabel glanced down at her hand. "Ah man!" Putting down the match to the pig's chosen card, she began the intricate series of jumps that was the penalty. As she was hopping around, she glanced out the window towards the setting sun—it was getting a bit late. Reflexively she checked the back corner of her mind where the sense of Dipper resided.

Stan yawned in boredom; it was obvious that "McToughins" was going to win. His eyes darted to his watch for the third time in as many minutes.

_Scuff…scratch…scuff…scratch…_

Mabel was jumping again; he sighed and dragged his attention back to the TV.

_Scuff…scrat—_

He turned in the armchair to face his great-niece. Mabel was standing stock still in the center of the room; her head was tilted down and held slightly at an angle, like she was listening for something. Stan could see her eyebrows furrow downward into a frown as she began to turn slowly, tilting her head further. The girl had done almost a full circle before she suddenly bolted for the door, hair streaming out behind her like a flag. Before he could leap from his chair the front door had already slammed.

"Mabel? Mabel!" The old man hurled himself after her and cleared the front porch just in time to see her disappear into the forest.

Mabel's breath filtered raggedly through her lungs as she raced through the ever darkening forest. The trees around her all became sinister figures as she plunged deeper and deeper into their midst, only a few fireflies were awake to light up the darkness. She hadn't been prepared for the flash of fear she'd received when prodding her connection to Dipper; it had warranted further checking, after all he could have just tripped or something. A second check had given her not only a spike of utter terror but a sharp sensation of pain—she hadn't even felt herself running until she was off the porch. Concentrating now, she checked the link again and nearly stumbled as a wave of fear washed over her mind; shaking off the effects, she veered slightly right and kept on running.

Dipper was running too. He'd only planned to find the Hide Behind today, not this monster! It had only taken ten minutes of walking before he'd heard the sinister "_chchchchch"_ sound that accounts claimed was the creature, but of course there had been nothing when he'd whirled around. It had taken hours of painstaking work to isolate his pursuer to a tiny copse of trees, there had been a cave nearby which he assumed was the Hide Behind's home.

He'd assumed wrong.

Pulling out a mirror from one of his inner vest pockets, Dipper had begun to turn a circle in the hopes that he would catch sight of the elusive cryptid. It had only just been getting dark then, and the pines around him had seemed to grow taller in the evening shadows. The moss under his shoes had been springy, and the forest around him had been unusually silent. Then he'd heard the sound.

"_CHCHCHCHCHCH"_

That had sounded like the Hide Behind, but it was so much louder—seeming to echo off of the tree trunks and reverberate from the rocks. It was almost like a battle cry…or a warning.

Dipper hadn't had time to contemplate the unusual call before soft footsteps had sounded from the cave, getting closer and closer. Quickly the boy had spun, facing the ominous hole that yawned before him like an infernal mouth. What emerged had made him regret not running immediately.

It was tall and dark, humanoid in shape—though no human could ever match up to this creature. Skin like rotting paper, fingers like long knives, legs like a scarecrow, and eyes like the Devil; it was garbed in what appeared to be skins. Dirty, straw colored hair stuck out from under a tall hat, and a long nose protruded from the ghastly face, crooking twice before tapering into a point. The eyes were sunken pits from which glowed two ethereal blue eyes, glinting with malice and lacking pupils or whites. It walked on two long, spindly legs, its arms hanging almost to its knees. Strangely, it didn't appear to have a mouth.

Dipper had stood rooted to the spot as the eight-foot-tall being approached him. Lowering its face until it could look the petrified boy in the eyes, the creature's face split just under the nose, opening until the dark mouth spread almost from ear to nonexistent ear.

It spoke only one word:

"_Fear._"

That had been enough for Dipper; he'd turned and run as if the hounds of Hell were chasing him, the mirror forgotten in the eerie copse. His chest heaving, the boy jumped fallen trees and skirted undergrowth, struggling to see as the evening closed in around him. The boy had chanced a look backwards, only to scream as he saw the creature barely a yard behind him; one long arm had shot out and raked his arm, sending a ribbon of red streaming down to his fingertips. Putting on a burst of speed, Dipper continued to sprint for his life through the darkening forest.

Crashing through the trees, holding his arms up to deflect dead branches, Dipper turned to risk another glance behind him, but was forestalled when he hit something—hard.

"Ooof!"

That wasn't his voice, that was—"Mabel!" Dipper hauled his twin to her feet. This was bad; he didn't want her out here!

"Dipper!" She shook leaves from her hair, "It felt like you were in—you're bleeding!"

Dipper whirled and scanned the forest around them, he couldn't see the monster, but it was so dark now. Visibility was limited to only a few feet.

"Mabel, we have to get back to the Mystery Shack! It isn't…safe…" He trailed off as a dark figure stepped from behind one of the larger trees.

"What is that?" His sister's voice was taut.

"Not good."

They began backing away as the monster drew closer and closer, its rank breath stealing over them like a cloud of toxic fumes.

"_Fear._" It cooed.

"Get away!" Mabel reached into a pocket and drew out her trusty grappling hook. "Go away you creep!"

"Mabel, I don't think that's going to help." Dipper tried to pull his sister back as she took a pace towards the thing.

The monster tilted its head in confusion, studying the small girl who was waving her weapon in a warning manner.

"_No fear?_" It murmured sadly, almost petulantly.

Dipper sucked in a breath as the creature frowned and drew back one long arm; his brain began to race. It was going to hit her. He could push her, but that would move her closer to it, he could pull her, but its arms were so long that he'd never get his sister completely out of the way. Mabel's brave expression was quickly morphing into one of fear as she realized what was about to happen to her. The creature's arm began to descend, and Dipper grabbed Mabel by the shoulders, spinning until his back was to the creature and his face was towards his sister.

Mabel didn't even have time to blink. Her brother's face appeared before her, etched with a determination that quickly turned to shock as there was a sound of rending fabric. Then she was jolted sideways as Dipper was ripped away from her, the momentum slamming him into a tree with a sickening _crack_ before he slid to the ground.

Mabel's twin sense cut out. The world seemed to tilt at an alarming angle, the ground opening up and yawning wide as if to swallow her whole. Trees blurred and spun around her as the universe flipped upside down and inside out. Someone—was that her?—was making a horrible high pitched sound, and the creature was forgotten as gravity seemed to draw her towards the limp form of her brother. Her peripheral vison faded to shapes and shadows as Mabel knelt and pulled Dipper up into her arms. A trickle of blood was starting at the corner of his mouth, and more was dampening the back of his head; she hated the sight of that blood, and wanted nothing more than to wipe it away as if it didn't exist. More important things came first.

"Dipper!" Her voice sounded strange in her own ears, like it was someone else's. She pushed one of her cheeks, which was wet with tears, against her twin's. "Don't leave me Dipper, please!"

The creature, meanwhile, was watching the proceedings with satisfaction. All the lovely fear, it was like a feast.

The world suddenly righted around Mabel as Dipper drew a shuddering breath, and then another. The back corner of her mind flared into awareness again. Her own sides were heaving with stress and the breath was sobbing in her throat.

Stan Pines had trailed his niece as closely as he could, given the circumstances. He guessed that if she was trying to get to Dipper, she would travel in a straight line, so the direction she had started in was a safe bet for him to follow. The man's anxiety had increased as the light had faded further and further, leaving him running in the semi-darkness. A sudden keening wail had stopped him in his tracks as it echoed around the eerie forest. That had sounded alarmingly like Mabel, and he didn't dare think of what could cause that chilling noise to emanate from his normally jovial niece. He took off in the direction of the sound, snatching at a dead branch lying against a tree as he went. Crashing through the undergrowth, Stan ground to a halt as he took in the scene before him.

Some sort of monster had his great niece and nephew cornered against a large tree. Mabel was kneeling, holding on to a _not dead not dead oh please, God, not dead_ Dipper. The girl was barely paying attention to the threat, only having eyes for her twin, whom she shielded as best she could with her body. Adrenaline and anger pumped through Stan's body, and the creature barely had time to register the new arrival before a weighty pine bough smashed into its shoulder. The monster reeled back with a cry of surprise and pain as Stan took up a position in front of the children.

Stanford Pines was quite a sight to see. His shoulders were up and his head down, eyes narrowed dangerously as he swung the pine branch again, warding off the monster.

"_No fear._" The creature's voice was not petulant now, it was apprehensive. The two smaller humans had been easy prey, but this larger one was a different matter altogether.

Drawing back an arm, the creature swung and regretted it when the pine branch slammed into its wrist with a crunching of bones. Shocked, it took a step back.

Stan advanced, voice cold with fury. "You get _away_ from my family."

The monster hesitated; this was not normal behavior from its prey. They weren't supposed to attack, and they certainly weren't supposed to threaten!"

"Get out of here!" Stan sent the pine branch swishing through the air again. "Get away or I'll smash your brains in!"

That was it for the monster, it wasn't willing to risk the wrath of this frightening human. With a last hiss of defiance the creature slunk into the darkness, casting a last hateful glance over its shoulder before disappearing entirely. It would find easier prey elsewhere.

Stan swung around, dropping the branch and kneeling beside Mabel. Reaching out, he tried to touch Dipper but was forced to recoil when his normally sweet niece snapped at him like a rabid animal.

"No!" She hunched her shoulders and turned further, trying desperately to block her brother from this interloper. Sensing movement, she raised one arm and waved it wildly in a futile attempt to beat back the attacker, only to yelp when it was caught in an iron grip.

"Mabel! Mabel it's me!"

She knew that voice, she could trust that voice, right? What if it was a trap? Mabel tried to yank her arm from the vice-like grasp, but was spun around until she was face to face with her Uncle.

"Mabel, I need to look at Dipper." He spoke quietly and calmly, trying not to startle her into another attempted attack. He could see tear tracks glistening on her cheeks.

Uncertainly, Mabel nodded and turned, exposing her brother to their guardian. "Kay."

Stan bit back a swear when he got a good look at the state of his nephew. Dipper's hair was damp with blood, and more was trickling from the corner of his mouth; a slash on his arm was dripping red. Panic welled up and he squashed it down, he couldn't afford to lose control right now. Leaning forward, Stan heaved a sigh of relief when he heard the boy's ragged breathing. Carefully the man scooped up his nephew's small form in one arm, cradling Dipper against his chest. The other arm came up so that Stan could pinch the bridge of his nose and wipe misty eyes, he was too old for stress like this.

"What did I tell ya', kid." His voice was soft. "That journal is nothin' but trouble."

The kid was in for one heck of a lecture when he rejoined the land of the living. Dipper was too curious, too daring, a lot like someone Stan had known a long time ago… He worried constantly about the trouble his great-nephew was undoubtedly getting into, and now he'd worry more. These twins were like his own children now, he would need to do a better job of protecting them.

Dipper, only barely conscious, was operating on base instincts. He could sense Mabel nearby, and was aware of a large, comforting presence surrounding him. There was breathing and a heartbeat just by his left ear, and the familiar sounds conveyed safety to his foggy mind. Words produced a rumbling vibration, his brain was too exhausted to translate them, but the timbre was reassuringly human.

Stan looked down as Dipper shifted slightly, turning his face so that he could bury it in his uncle's shirt; the arm that had been draped over the narrow chest moved until his nephew's small hand could grip feebly at the rough fabric. The gesture was so young, so innocent, that Stan's gaze couldn't help but soften. Slowly the man stood, being careful not to jostle his precious burden. Beside him Mabel gripped one of his coat-tails and scrubbed at her eyes with one hand.

She looked up in surprise as her uncle addressed her.

"Good job, kid. No telling what would've happened if you hadn't found him."

Mabel looked away, it was because she'd found him that he'd gotten hurt. She couldn't bring herself to say it though, it was too painful for words.

"C'mon, kid." Stan Pines turned towards home. "We need to get your brother some first aid."

Behind them the forest was silent and eerie as the animals hid from the creature stalking the night. It would kill before the sun rose, but it would never again hunt those two small humans for fear of the larger one's wrath. Even monsters had their limits.

Author's note! Hello All! I would just like to inform you that inspiration for this fic came from these two picures:

art/Don-t-leave-me-Dipper-please-423105106 by Cherryviolets

post/93936208919/gf-whatditellya by Junryou


	2. Author's Note

Hi, guys! I only just checked my email yesterday and saw that a bunch of people followed this. While I appreciate the support, I feel obligated to tell you that this is a one-shot. Upon further investigation I noticed that goofed and didn't listen when I told it that this was complete. I apologize for the confusion. This does NOT mean that I won't be writing any more Gravity Falls stories, it just means that there probably won't be a continuation of this one. Thanks again and have a nice day!


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